CN108087871A - A kind of coal burner - Google Patents

Abstract

The invention relates to a pulverized coal burner, which belongs to the technical field of pulverized coal combustion equipment. It is equipped with a pre-combustion chamber inside, and also includes a microwave plasma ignition assembly, a primary air assembly and a secondary air assembly. There are connected and parallel primary pre-combustion chambers and secondary pre-combustion chambers. The primary air assembly includes a primary air main pipe, a pulverized coal concentrator and an air duct partition. The present invention generates high-temperature plasma by means of a microwave plasma ignition assembly. As a high-temperature ignition or combustion-supporting heat source, it enhances the stability of combustion at low loads, and is especially suitable for situations where the boiler frequently starts and stops and the load changes greatly. Separating the primary air from thick and thin helps to stabilize combustion and reduce the emission of nitrogen oxides. At the same time, with the help of the dense primary air annular channel and the secondary air channel, the coking phenomenon in the pre-combustion chamber is avoided, so as to achieve high-efficiency and low-pollution combustion at full load.

Description

a pulverized coal burner

technical field

The invention belongs to the technical field of pulverized coal combustion equipment, and in particular relates to a pulverized coal burner.

Background technique

Compared with large-capacity power plant boilers, coal-fired industrial boilers have the characteristics of small coal-fired flow and small furnace volume, which makes it difficult to control the stable combustion of the burner, heat flow and combustion in the furnace, and restricts the coal-fired industry. Comprehensive promotion and application of boilers.

In recent years, several types of burners for coal-fired industrial boilers have appeared on the market. Among them, Beijing Coal Science and Technology Research Institute Co., Ltd. designed a center reverse injection double cone burner by referring to the combustion organization principle of Dr.schoppe burner. Compared with other swirl burners, this burner has a separate double cone recirculation chamber (Pre-combustion chamber), the recirculation zone is formed by the rotating secondary air flow field, and the high-temperature flue gas reflow is strengthened by the reverse injection of the primary air (powdered coal-air mixture) center, which advantageously strengthens the gasification and ignition of the pulverized coal airflow in the recirculation chamber. Combustion is conducive to ignition and combustion. At the same time, there are also problems such as coking on the wall of the reflow chamber (especially near the outlet), overheating and deformation of the powder injection tube, and high concentration of nitrogen oxide emissions. The Shanghai Special Equipment Supervision and Inspection Technology Research Institute has designed a low-flow pulverized coal stable combustion burner, which uses the function of the internal secondary air cyclone and the blunt body set at the outlet of the primary air-powder mixture channel to form a stable recirculation zone. The recirculation zone is filled with high-temperature flue gas reflowed from the center of the furnace, and a turbulent mixing zone of combustible gas powder mixture and hot recirculation flue gas is formed in the area between the outside of the recirculation zone and the main flow zone. Due to the large radial velocity gradient at the boundary, there is a strong exchange of mass, momentum and energy between the combustible mixture and the high-temperature flue gas, and the combustible mixture is continuously heated up until it reaches the ignition temperature and starts to ignite. At the same time, the flame flows from the inside to the outside Propagation, the heat is transferred to the returning flue gas, so that the flue gas will bring the heat energy to the upstream, and then transfer the heat to the new combustible mixture to form a stable combustion in the pre-combustion chamber. Although the fullness of this design is good, it also forms a flow field and temperature environment that is easy for the pulverized coal to ignite and burn. However, the high-temperature flue gas mixes with the secondary air too early, and the flame is too close to the wall of the pre-combustion chamber, causing slagging on the wall. bad question.

At the same time, in the field of power plant boiler burners, in order to reduce the cost of ignition oil, various relevant units have successively developed new ignition technologies for pulverized coal boilers, such as plasma ignition technology, micro-oil ignition technology, and oxygen-enriched ignition technology. Conventional plasma ignition technology uses direct current (280-350A) to contact arc ignition under the condition of medium pressure 0.01-0.03MPa, and obtains stable power DC air plasma under strong magnetic field. Compared with traditional fuel oil, it has the characteristics of economy, environmental protection, high efficiency, simplicity and safety, and is a substitute product for the transformation of the current fuel system. However, the burner that uses the plasma arc to ignite pulverized coal generally adopts the axial insertion method of the plasma generator. The primary air duct is equipped with multi-stage guide tubes, and the pulverized coal is distributed step by step. After the flame is ignited, the pulverized coal entering the secondary guide tube is ignited again, and by analogy, the pulverized coal in the remaining guide tube is ignited in turn. Generally, the guide tube is divided into three levels, and a thick-thin guide ring is set in each level of the guide tube and the primary air duct, so that the dense-phase coal powder enters the central area, which is convenient for the ignition of the coal powder. This kind of burner generally changes the original burner greatly, so that the flow field, temperature distribution inside the burner, and the combustion area at the nozzle all change, and the dense phase coal powder is distributed along the center line of the burner, not only It affects the performance of the burner, making the burner unable to restore the original state of separation of pulverized coal concentration and light, and destroying the temperature distribution at the burner nozzle entering the furnace.

Contents of the invention

Aiming at the various deficiencies of the prior art, in order to solve the above problems, a pulverized coal burner is now proposed.

To achieve the above object, the present invention provides the following technical solutions:

A pulverized coal burner, which is provided with a pre-combustion chamber inside, and also includes a microwave plasma ignition assembly, a primary air assembly and a secondary air assembly, and the inside of the pre-combustion chamber is provided with a connected and parallel primary and a secondary pre-combustion chamber, the primary pre-combustion chamber is located at the inlet end of the secondary pre-combustion chamber, the outlet end of the secondary pre-combustion chamber communicates with the boiler furnace, the microwave plasma ignition assembly and the primary air assembly are located at The inlet end of the primary pre-chamber, and the microwave plasma ignition assembly coincides with the central axis of the primary pre-chamber, and the secondary air assembly is sleeved on the periphery of the pre-chamber;

The primary air assembly includes a primary air main pipe, a pulverized coal concentrator and an air duct partition. The primary air main pipe includes vertical and connected vertical air ducts and horizontal air ducts. Located inside the vertical air duct, the primary pre-combustion chamber is located inside the horizontal air duct, the air duct partition is arranged along the vertical direction and connected with the outer wall of the primary pre-combustion chamber, and it divides the vertical air duct into A thick primary air duct and a light primary air duct, the thick primary air duct communicates with the inlet end of the primary pre-combustion chamber, the light primary air duct communicates with the inlet end of the secondary pre-combustion chamber, and the rich primary air duct The diameter of the pipe is smaller than that of the primary air duct.

Further, the primary pre-chamber and the secondary pre-chamber are both cylindrical structures, and the outer wall materials of both are stainless steel plates.

Further, the inlet end of the secondary pre-combustion chamber is set facing the horizontal air duct, and the diameters of both are the same, and there is a gap between the outer wall of the primary pre-combustion chamber and the outer wall of the horizontal air duct to communicate with the primary air duct. The light primary wind circular channel.

Further, an inclined partition is provided at the joint between the air channel partition and the outer wall of the primary pre-combustion chamber, and a cone is provided at the joint between the vertical air duct and the horizontal air duct, and the conical surface of the cone is in contact with the outer wall of the primary pre-combustion chamber. The inclined partitions are parallel, and there is an annular passage for the concentrated primary air communicated with the concentrated primary air passage between them.

Further, the annular channel of the weak primary air communicates with the inlet end of the secondary pre-combustion chamber, and the annular channel of the rich primary air communicates with the inlet end of the primary pre-combustion chamber.

Further, the angle between the inclined partition and the horizontal plane is 30°-40°.

Further, the secondary air assembly includes a secondary air inlet, an air box and a swirler, the air box is sleeved on the periphery of the pre-combustion chamber, the secondary air inlet and the swirler are respectively located at both ends of the air box, and The swirler is located at the inlet end of the pre-chamber.

Further, there is a secondary air channel communicating with the swirler between the outer wall of the secondary pre-combustion chamber and the outer wall of the pre-combustion chamber, and the outlet end of the secondary air channel communicates with the boiler furnace.

Further, the microwave plasma ignition assembly includes a microwave plasma generator and a microwave generator, the plasma nozzle of the microwave plasma generator communicates with the inlet end of the first-stage pre-combustion chamber, and the two are facing each other, and the microwave The generator is connected with the microwave plasma generator through a microwave coupling tube.

The beneficial effects of the present invention are:

High-temperature plasma is generated by means of microwave plasma ignition components as a high-temperature ignition or combustion-supporting heat source, which enhances the stability of combustion at low loads, and is especially suitable for situations where the boiler frequently starts and stops and the load changes greatly. Separating the concentration of primary air is helpful Because of the stable combustion, the generation of nitrogen oxides is reduced, and the combustion efficiency is improved. At the same time, with the help of the dense primary air annular channel and the secondary air channel, the coking phenomenon in the pre-combustion chamber is avoided, so as to achieve full-load high-efficiency and low-pollution combustion.

Description of drawings

Fig. 1 is the overall structural representation of the present invention;

Fig. 2 is a schematic structural diagram of the primary air component.

In the drawings: 1- pre-combustion chamber, 2- primary pre-combustion chamber, 3- secondary pre-combustion chamber, 4- primary air duct, 401- vertical air duct, 402- horizontal air duct, 5- primary air, 6-secondary air, 7-secondary air inlet, 8-air box, 9-cyclone, 10-microwave plasma generator, 11-microwave generator, 12-coal powder concentrator, 13-air duct partition , 14-concentrated primary air duct, 15-light primary air duct, 16-inclined partition, 17-concentrated primary air annular channel, 18-light primary air annular channel, 19-secondary air channel, 20-conical body.

Detailed ways

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with the accompanying drawings of the present invention. Based on the embodiments in this application, those of ordinary skill in the art will Other similar embodiments obtained without creative work shall all fall within the scope of protection of this application. In addition, the directional words mentioned in the following embodiments, such as "upper", "lower", "left", "right", etc., are only referring to the directions of the drawings, therefore, the directional words used are for illustration rather than limitation invent.

Embodiment one:

As shown in Figure 1-2, a pulverized coal burner has a pre-combustion chamber 1 inside, and also includes a microwave plasma ignition assembly, a primary air assembly and a secondary air assembly. Wherein, the inside of the pre-chamber 1 is provided with a connected and parallel primary pre-chamber 2 and a secondary pre-chamber 3, the primary pre-chamber 2 is located at the inlet end of the secondary pre-chamber 3, And the outlet end of the secondary pre-combustion chamber 3 communicates with the boiler furnace.

The microwave plasma ignition assembly is located at the inlet end of the primary pre-chamber 2, and the microwave plasma ignition assembly coincides with the central axis of the primary pre-chamber 2, and the microwave plasma ignition assembly includes a microwave plasma generator 10 and a microwave generator device 11, the plasma nozzle of the microwave plasma generator 10 communicates with the inlet end of the primary pre-combustion chamber 2, and the two are facing to each other, and the microwave generator 11 is connected to the microwave plasma generator 10 through a microwave coupling tube connect. That is to say, the microwave plasma generator 10 converts the microwave generated by the microwave generator 11 into plasma, which plays the role of coal powder ignition and combustion support. At the same time, the microwave plasma generator 10, the primary pre-combustion chamber 2, and the secondary pre-combustion chamber 3 are connected in series to amplify the heat, and use a small amount of electric energy to ignite more pulverized coal, so that the pulverized coal is basically Gasification is beneficial to the continuous combustion and burnout of unburned pulverized coal and gaseous combustibles in the boiler furnace.

The primary air assembly is located at the inlet end of the primary pre-combustion chamber 2 , and includes a primary air main pipe 4 , a pulverized coal concentrator 12 and an air duct partition 13 . The primary air duct 4 includes a vertical and connected vertical air duct 401 and a horizontal air duct 402, the pulverized coal concentrator 12 and the air duct partition 13 are located inside the vertical air duct 401, and the primary pre-combustion chamber 2 Located inside the horizontal air duct 402. The pulverized coal concentrator 12 separates the primary air 5 (powdered coal air mixture) into thick and light two strands, i.e. thick primary air and light primary air. The outer walls of the pre-combustion chamber 2 are connected, and it divides the vertical air duct 401 into a rich primary air channel 14 and a weak primary air channel 15, which are used to divert the rich primary air and the light primary air respectively. The thick primary air channel 14 communicates with the inlet end of the primary pre-combustion chamber 2, and the light primary air channel 15 communicates with the inlet end of the secondary pre-combustion chamber 3, and the diameter of the rich primary air channel 14 is smaller than that of the light primary air channel. The pipe diameter of the air duct 15, that is to say, a small amount of concentrated primary air enters the first-stage pre-combustion chamber 2, and a plasma flame (about 4000° C.) with less energy can be used to rapidly heat and decompose the coal powder in the concentrated primary air to form a high temperature Gas (temperature is 1100-1200°C), then the high-temperature gas enters the secondary pre-combustion chamber 3, meets the light primary air, and under the action of high-temperature gas heating and combustion heat release, the coal powder in the light primary air is burned and gasified .

Both the primary pre-combustion chamber 2 and the secondary pre-combustion chamber 3 are in a cylindrical structure, and the outer walls of both are made of stainless steel plates and lined with heat-resistant materials. The inlet end of the secondary pre-combustion chamber 3 is arranged facing the horizontal air duct 402, and the diameters of the two are the same, and there is a weak primary air between the outer wall of the primary pre-combustion chamber 2 and the outer wall of the horizontal air duct 402. The light primary air annular channel 18 communicated with the road 15, and the light primary air annular channel 18 communicates with the inlet end of the secondary pre-combustion chamber 3, that is to say, the light primary air enters the secondary pre-combustion chamber 3 in a ring shape to avoid coking Phenomenon. At the same time, an inclined partition 16 is provided at the junction between the air duct partition 13 and the outer wall of the primary pre-combustion chamber 2 , and in this embodiment, the air duct partition 13 and the inclined partition 16 are integrally formed. The junction of the vertical air duct 401 and the horizontal air duct 402 is provided with a conical body 20, the conical surface of the conical body 20 is parallel to the inclined partition 16, and there is a gap between the two that communicates with the primary air duct 14. The thick primary air annular passage 17, and the thick primary air annular passage 17 is connected with the inlet end of the first-level pre-combustion chamber 2, that is to say, the thick primary air enters the first-level pre-combustion chamber 2 in a ring shape, and the plasma flame is blown by the thick primary air. Surrounding, in order to strengthen the mixed heating of the concentrated primary air and the plasma flame, the angle between the inclined partition 16 and the horizontal plane is 30°-40°, so that the concentrated primary air is sprayed into the plasma flame at a certain angle.

The secondary air assembly is sleeved on the periphery of the pre-combustion chamber 1, and includes a secondary air inlet 7, an air box 8 and a swirler 9, the wind box 8 is sleeved on the periphery of the pre-chamber 1, and the secondary air The air inlet 7 and the swirler 9 are respectively located at both ends of the wind box 8, and the swirler 9 is located at the inlet end of the pre-combustion chamber 1, that is to say, after the secondary air 6 enters, it flows in the opposite direction to the inlet end of the burner . A secondary air channel 19 communicated with the swirler 9 is left between the outer wall of the secondary pre-combustion chamber 3 and the outer wall of the pre-combustion chamber 1, and the outlet end of the secondary air channel 19 communicates with the boiler furnace, that is, The high-temperature gas (temperature 800-900°C) leaving the secondary pre-combustion chamber 3 meets the secondary air in the boiler furnace to form a swirling combustion flow field, which is conducive to stable combustion and burnout. At the same time, the primary pre-combustion The interior of the chamber 2 and the secondary pre-combustion chamber 3 is a strong reducing atmosphere, which is beneficial to suppress the generation of nitrogen oxides.

The present invention has been described in detail above. The foregoing description is only a preferred embodiment of the present invention, and should not limit the implementation scope of the present invention. within the scope of the invention.

Claims (9)

1. A pulverized coal burner, which is provided with a pre-combustion chamber inside, is characterized in that it also includes a microwave plasma ignition assembly, a primary air assembly and a secondary air assembly, and the inside of the pre-combustion chamber is provided with connected and parallel The primary pre-combustion chamber and the secondary pre-combustion chamber, the primary pre-combustion chamber is located at the inlet end of the secondary pre-combustion chamber, the outlet end of the secondary pre-combustion chamber communicates with the boiler furnace, and the microwave plasma ignition The component and the primary air component are located at the inlet end of the primary pre-combustion chamber, and the microwave plasma ignition component coincides with the central axis of the primary pre-combustion chamber, and the secondary air component is sleeved on the periphery of the pre-combustion chamber; The primary air assembly includes a primary air main pipe, a pulverized coal concentrator and an air duct partition. The primary air main pipe includes vertical and connected vertical air ducts and horizontal air ducts. Located inside the vertical air duct, the primary pre-combustion chamber is located inside the horizontal air duct, the air duct partition is arranged along the vertical direction and connected with the outer wall of the primary pre-combustion chamber, and it divides the vertical air duct into A thick primary air duct and a light primary air duct, the thick primary air duct communicates with the inlet end of the primary pre-combustion chamber, the light primary air duct communicates with the inlet end of the secondary pre-combustion chamber, and the rich primary air duct The diameter of the pipe is smaller than that of the primary air duct. 2. A pulverized coal burner according to claim 1, characterized in that, the primary pre-combustion chamber and the secondary pre-combustion chamber are both cylindrical structures, and the outer wall materials of both are stainless steel plates . 3. A pulverized coal burner according to claim 2, characterized in that, the inlet end of the secondary pre-combustion chamber is arranged facing the horizontal air duct, and both have the same diameter, and the primary pre-combustion chamber A light primary air annular passage communicated with the light primary air duct is left between the outer wall of the horizontal air duct and the outer wall of the horizontal air duct. 4. A pulverized coal burner according to claim 3, characterized in that an inclined partition is provided at the joint between the air passage partition and the outer wall of the primary pre-combustion chamber, and the vertical air duct and the horizontal A conical body is provided at the junction of the air ducts, the conical surface of the conical body is parallel to the inclined partition, and there is an annular passage for the concentrated primary air communicating with the concentrated primary air passage between the two. 5. A pulverized coal burner according to claim 4, characterized in that, said light primary air annular channel communicates with the inlet end of the secondary pre-combustion chamber, said thick primary air annular channel communicates with the primary pre-combustion chamber The inlet end of the chamber is connected. 6. A pulverized coal burner according to claim 4, characterized in that the angle between the inclined partition and the horizontal plane is 30°-40°. 7. A pulverized coal burner according to any one of claims 2-6, characterized in that, the secondary air assembly includes a secondary air inlet, an air box and a swirler, and the air box is sleeved on the pre-combustion The periphery of the chamber, the secondary air inlet and the swirler are respectively located at both ends of the air box, and the swirler is located at the inlet end of the pre-combustion chamber. 8. A kind of pulverized coal burner according to claim 7, it is characterized in that, there is a secondary air passage communicated with the swirler between the outer wall of the secondary pre-combustion chamber and the outer wall of the pre-combustion chamber, The outlet end of the secondary air channel communicates with the furnace of the boiler. 9. A kind of pulverized coal burner according to claim 7, it is characterized in that, described microwave plasma ignition assembly comprises microwave plasma generator and microwave generator, and the plasma spout of described microwave plasma generator is connected with primary The inlet end of the pre-combustion chamber is communicated, and the two are arranged facing each other, and the microwave generator is connected with the microwave plasma generator through a microwave coupling tube.